Method for preparing yarn from fibers



United States Patent 3,310,935 METHQD FOR PREPARING YARN FRQM FIBERS Otto B. Wurzburg, Whitehouse Station, and Herbert (3. Olsen, Berkeley Heights, Ni, and John F. Fitzgerald, Scarsdale, N.Y., assignors to National Starch and Chemical Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 2, 1963, Ser. No. 269,867 7 Claims. (Cl. 57-456) This invention relates to an improved method for preparing yarns from natural and synthetic fibers. More particularly, it relates to the use, in the yarn making process, of certain additives which efiect significant improvements in the process itself, as Well as in the yarns thereby produced.

Industrial methods of reparing yarn from natural fibers involve a number of processing steps. The yarn making process usually begins with the so-called opening operation wherein the compacted bales of fibers are pulled apart so as to permit the fibers to bloom and condition in an atmosphere of controlled humidity. After the opening operation, the fibers are blended in preparation for the subsequent picking step, wherein the fiber stock is opened further, cleaned if necessary, and for-med into a uniform fiber sheet called a lap. The laps of fibers are then subjected to the carding operation which opens the stock still further, cleans the fibers, and produces a continuous strand of loosely assembled fibers commonly referred to as a sliver. The carding operation is frequently followed by the combing step which serves to remove short fibers, neps (small entanglements of fibers), and any dirt remaining in the fibers. The combing step also functions to align the fibers in parallel relationship. The fibers are then further parallelized and the slivers uniformity is improved in the drawing step by passing the sliver through pairs of rolls moving with progressively higher surface speed. The next step in the yarn making process is the roving operation which reduces the drawn sliver to a suitable size for spinning and which also improves the uniformity of the sliver. The resulting roving is a continuous strand of fibers which has been slightly twisted in order that it may have sufficient strength to undergo the spinning operation which is to follow. This Spinning step further attenuates the roving and imparts thereto a twist for added strength. As desired, the twisted yarn may be subjected to winding and to further twisting.

The yarn making process described hereinabove is beset by several serious difiiculties. The complexity of the process and the multiplicity of the steps involved therein inevitably increase the chance of mishap occurring in the process. For example, it has been a commonplace occurrence in the conventional yarn making process for the sliver of fibers to break under the rigors of the spinning operation, thereby resulting in a costly slow-down of production. Moreover, the yarn produced by the methods heretofore utilized has often exhibited deficiencies in tensile strength and in uniformity. Lastly, among the least desirable features of the yarn making operations hitherto utilized has been the length of time necessitated by the various process steps.

It is an object of this invention to provide an improved method of preparing yarn from natural and synthetic fibers. A further object of this invention is to provide a method of preparing yarns having improved properties of tensile strength and uniformity. A still further object of this invention is to significantly shorten the time required in the manufacture of yarn from natural and synthetic fibers. Other objects and the advantages of this invention will be apparent from the discussion that appears hereinafter.

the fibers are first assembled into a continuous strand or sliver. The addition to the fibers of the starch product not only reduces the time required for subsequent process steps which must be carried out, but also effects a significant improvement in the strength and uniformity of the finished yarn.

As used herein, the term starch is meant to encompass amylaceous substances such as native starch as well as dextrinized, hydrolyzed, oxidized, esterified, and'etherified starches, and components of starches, i.e., amylose and amylopectin, still retaining their substantially amylaceous characteristics and whose granule structure may be either intact or in disrupted form. These starches may be derived from any source, including com, high amylose corn, sago, wheat, rice, sweet potato, sorghum, waxy sorghum, waxy maize, potato, or tapioca starch.

For the purposes of this invention, the term starch product comprises any starch which has been chemically or physically modified and/ or blended with a flow agent, hereinafter described, so as to be converted into a free flowing material having a certain critical particle size and a specified flow characteristic.

Of particular utility in the process of our invention are those starches which have been treated to exhibit hydrophobicity to such an extent that they are resistant to being wet by water. These hydrophobic starch products, which are particularly useful in the yarn making process under conditions of high humidity, should also show fluidity or mobility in the powdered form.

The degree of mobility, i.e., the flow character, of these starch products should be such that, when subjected to the flow rating evaluation test described hereinafter, the starch product will display a fiow rating of at least about 1.20. In conducting this flow rating evaluation test, use is made of a Vibra-Flow Feeder, made by the Syntron Company, Homer City, Pa. The feeder consists of a brass plate, 9" x 20", with means to cause it to vibrate in the direction of its long axis. The plate is inclined at an angle of 4 /2 The starch product to be tested is molded, by means of a brass mold, into the shape of a flat top cone with a 1" bottom diameter, the starch cone being placed on the plate at a point 5%" up from the edge of its 9" side and 2 /2 .in from the edge of its 20" side. A similar cone is placed 2 /2" in from the opposite edge of the 20" side of the plate. This latter cone, which is the control or standard, is made from untreated, powdered corn starch containing aproximately 1.1%, by weight, of moisture.

When the two starch cones have been placed on the plates, vibration is begun, with the feeder adjusted to a vibration setting of 55, whereupon the cones break down, spread out and then proceed up the incline along the long axis, i.e., the 20" length, of the plate. The time taken for the standard material as well as the material being tested to pass completely oif the top of the plate is carefully measured. The greater the period required for the starch product to pass off the plate, the better the flow properties. The flow rating is calculated by dividing the time taken by the product of the example to pass off the plate by the time taken by the untreated standard corn starch. Thus, a rating of 1.0 would indicate that the product of our invention had the same flow as untreated corn starch. A higher rating would indicate that the product of our invention took longer to pass off the plate and therefore had a correspondingly better fiow characteristic than untreated corn starch.

The starch products operable in the process of our invention should therefore have a flow rating, as determined by the above described method, of at least about 1.20. In addition, these starch products should have a particle size ranging from about 3 microns to about 100 microns.

Among the starch products which possess the necessary flow and size characteristics are the free flowing, hydrophobic starch derivatives of U.S. Patent 2,613,206 which are the products preferably used in our process. These derivatives comprise the reaction products of compounds containing a polyvalent metal ion and an ungelatinized starch acidester of a substituted dicar-boxylic acid of the formula:

9 0 StarchOi JRii-OH wherein R is a radical selected from the group consisting of dimethylene and trimethylene radicals and R is a hydrocarbon substituent selected from the group consisting of alkyl, alkenyl, aral-kyl, and aralkenyl substituents.

Also applicable are the starch products prepared as described in US. Patent 2,614,945 wherein starch granules are intimately mixed and coated, in the presence of moisture, with a finely divided, freshly precipitated water insoluble solid of smaller particle size than the starch granules, said water insoluble solid being selected from the group consisting of freshly precipitated, water insoluble inorganic salts and hydroxides.

Also operable are the starch products prepared as described in US. Patent 2,626,257 wherein a minor proportion of a flow agent selected from the group consisting of nickel, tin and magnesium oxides, and magnesium carbonate is admixed with a finely divided powder of nongelatinized starch granules which have been etheri-fied to a degree corresponding to treatment, in aqueous sus pension, with an agent causing formation of die-ther linkages wherein chains having more than one carbon separate the oxygen bonds, in an amount suificient to link l.7-4.5% of the free hydroxyl groups.

In addition, we can employ the starch products prepared according to US. Patent 3,071,492 wherein an aqueous starch slurry is treated with an aqueous solution of mono-sodium methyl siliconate; the starch products prepared according to US. Patent 2,647,892 wherein starch particles are coated with about 0.03 to 0.15% of a thermoset polymethyl siloxane resin; and, any starch mixed with one or more flow agents, i.e., materials which increase the mobility, and in some cases the hydrophobicity as well, of a starch. Among the flow agents which can be used are magnesium oxide, magnesium carbonate, magnesium stearate, tricalcium phosphate, zinc oxide, tin oxide, nickel oxide, titanium dioxide, and the like. These flow agents are generally admixed with a starch in a concentration of about 1.0% by weight of the starch. It should also be noted that these flow agents maybe admixed with any of the hydrophobic starch products operable in our process.

As was mentioned previously, the starch products may be incorporated in the fiber at any point prior to the carding operation. Thus, for example, these additives may be added by spraying or some other appropriate method at the point where the fibers are opened, at the blending step, or at any other point in the processing operation occurring before the fibers are formed into a continuous strand. In practice, the starch products can be used in amounts varying up to about 1%, by weight, as based on the weight of the fiber which is being processed.

The process of our invention, wherein the starch products heretofore described are incorporated, may be utilized to prepare yarns from any natural fiber such as cotton, wool, and silk, or from any combination of natural fibers with synthetic fibers such as rayon, polyamide, polyester, acetate, and acrylic fibers.

The use of the starch products in the yarn making in the efiiciency of the process itself and in the properties of the finished yarn. Thus, the yarn is characterized by higher tensile strength and fewer yarn breaks in the spinning operation. Moreover, due to the increased tensile strength of the yarn, it is not necessary to impart as much twist thereto as was formerly required in order to obtain a yarn of satisfactory strength. Since less twist is necessary to achieve a strong yarn, the time required to produce a satisfactory yarn is reduced with an attendant increase in rate of production. The finished yarn is further characterized by the absence of substantial amounts of trash because of the ease with which foreign matter is removed in the roving and carding steps. Moreover, the use of the starch products in our process produces a uniform yarn having few thick or thin spots and few neps.

The following examples Will further illustrate the embodiment of this invention.

Example I This example illustrates the significant improvements in tensile strength exhibited by yarns prepared by the process of our invention.

In this example and in the examples that follow, the starch product used in the yarn making process was a starch acid-ester of substituted succinic acid prepared according to Example IX of US. Patent 2,613,206 whereby corn starch is first reacted with octenyl succinic acid anhydride and then with aluminum sulfate. This product had a maximum particle size of 25 microns, was hy drophobic to the extent that it could not be wet by water, and it possessed a mobility such that it had a flow rating (as determined on the Vibra-Flow Feeder) of 2.20.

In this example and in the examples that follow, the conventional procedure described previously for the preparation of carded cotton yarns was utilized. The resulting yarn was reeled into yard skeins which were conditioned for 4 hours at 70 F. and 65% RE. The yarns were then broken on 21 Scott Pendulum Tester, a pendulum yarn tester of the type described in Section 5 of ASTM specifications D 76. The strength of the skeins is indicated by the Count-Strength Product, a greater strength being indicated by a higher Count-Strength Product (C XS), the latter value being the product of the counts (i.e., the fineness of yarn as represented by the number of yards per pound divided by 840) and the breaking strength of a standard skein of yarn. The amount of starch product utilized in our process and the point of the process at which it was added to the fibers are indicated in the following table.

Percent of starch Force Re- Sample product used Where Applied quired to OXS 0. (based on Break weight of Skein Obs.) cotton fibers) None 59. 3 1,772 0.25 Blltiander in opening 64. 4 1, 909

ne. 3 0.50 Beginning of picking 1, 924

operation.

From the results presented above, it can be seen that the addition of starch products in the yarn making process of our invention produces a yarn having a significantly higher tensile strength than yarn produced by a process wherein no such starch product was added.

Example 11 This example illustrates the significant improvements in uniformity exhibited by yarns prepared by means of the process of our invention.

The starch product described in Example I was utilized in a conventional procedure for making carded cotton yarns. In this example the uniformity of the slivers and rovings were tested on a Uster Evenness Tester equipped with a linear integrator, whereas the uniformity of the yarns was tested on the Uster Automatic Dynamometer.

The Uster Evenness Tester is a device which measures the variations in the properties of the strand as determined by changes in the capacity of a condenser when the strand is passed between its plates. The Uster Automatic Dynamometer is an instrument as described in ASTM designation D 1425-56T. The degree of uniformity is indicated by the non-uniformity percentage-the lower the non uniformity percentage, the higher the degree of uniformity.

In evaluating yarn imperfections, bobbins of yarn were tested on a Uster Evenness Tester equipped with a linear integrator and an imperfection indicator. Thin places refer to those imperfections within the yarn where there are appreciably fewer fibers per yarn cross-section compared to the average with respect to practical working tolerances. Thick places refer to those imperfections within the yarn where there are soft, thick and uneven areas. Neps refer to those imperfections in the yarn where there are small entanglements of fibers.

The following table sets forth the results of the aforedescribed uniformity tests.

From the results presented above, it can be seen that the addition of starch products in the yarn making process of our invention enables large amounts of waste matter to be removed early in the process.

Any departure from the above description which conforms to the present invention is intended to 'be included within the scope of the invention as defined by the following claims.

We claim:

1. In a method for preparing yarn from fibers, the step which comprises adding to the fibers prior to the assembling of said fibers, by carding, into a continuous strand, a finely powdered, free flowing starch product, and thereafter subjecting the resulting strand to a spinning operation for producing the yarn from said strand.

2. In a method for preparing yarn from fibers, the step which comprises adding to the fibers, prior to the assembling of said fibers, by carding, into a continuous strand, a finely powdered, free flowing starch product, said starch product having a particle size ranging from 3 to 100 microns and a flow rating of at least 1.20,

Percent of Percent Non-uniformity No. of Yarn Imperfections Sample starch product No. used (based Where Applied on wt. of aw g Roving Yarn Thin Thick Neps cotton fibers) Sliver places places None 5. 22 9. 66 17. 4 21 688 243 0. 25 Blender in opening line. 3. O3 7. 14, 2 7 479 182 0.50 Beginning of picking operat 3. 46 8. 04 14. 4 4 524 179 1. 0 Middle of operation 3. 76 9. 20 15. 1 9 605 172 From the results presented above, it can be seen that the addition of starch products in the yarn making process of our invention produces a yarn having a significantly higher degree of uniformity than yarn produced by a process wherein no such starch product was added.

Example III This example illustrates the more eflicient removal of trash from yarn which is achieved by the use of starch products in the process of our invention.

It is desirable to remove waste matter in the early preparatory stages of the yarn making process. Such waste matter, usually referred to as trash, consists of seed or vegetable matter, short fibers, lint and dirt. The table given below illustrates the greater amounts of waste matter which are removed in our process at early stages of the yarn making operation. In this example the starch product described in Example'I was utilized in a conventional procedure for making carded cotton yarns.

Percent Percent of Waste Point of Waste Starch Removal Removal and Product Where Applied (based on Sample No. (based on wt. of wt. of cotton cotton fibers) fibers) At carding step 1. None 3.10 At carding step 2... 0. 25 Blender in opening 3. 52

me. At carding step 3... 0.50 Beginning of picking 3. 41

operation. At carding step 4.-. 1. 0 Middle of picking 3. 75

operation.

Percent of Point of Waste Starch Grains of Removal and Product Where Applied waste/lb. Sample No. (based on of fiber wt. of cotton fibers) At roving step 1.--. None 4. 9 At roving step 2.-.- 0.25 Bllender in opening 8. 6

ne. At roving step 3.-.- 0. 50 Beginning of picking 5. 2

operation. At roving step 4--.- 1.0 Middle of picking 7. 0

operation.

and thereafter subjecting the resulting strand to a spinning operation for producing the yarn from said strand.

3. The method of claim 2 wherein said starch product is hydrophobic.

4. The method of claim 2 wherein said starch product is the reaction product of a compound containing a polyvalent metal ion and an ungelatinized starch acid ester of a dicarboxylic acid having the formula R o Starch0( )I t( J0H wherein R is a radical selected from the group consisting of dirnethylene and trimethylene radicals and R is a hydrocarbon substituent selected from the group consisting of alkyl, alkenyl, aralkyl, and aralkenyl substituents.

5. The method of claim 2 wherein said starch product comprises a starch mixed with a flow agent.

6. The method of claim 2 wherein said starch product is added to the fibers in an amount of up to 1%, by weight, of said fibers.

7. In a method for preparing yarn from cotton fibers, the step which comprises adding to the fibers, prior to the assembling of said fibers, by carding, into a continuous strand, a finely powdered, free flowing starch product, said starch product being the reaction product of a compound containing a polyv-alent metal ion and an ungelatinized starch acid-ester of a dicarboxylic acid having the formula wherein R is a radical selected from the group consisting of dirnethylene and trimethylene radicals and R is a hydrocarbon substituent selected from the group consisting of alkyl, alkenyl, aralkyl, and aralkenyl substituents, and thereafter subjecting the resulting strand to a spinning operation for producing the yarn from said strand.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Caldwell 117-139 Krisan 1l7-l00 Caldwell et al. l6792 La Bnie et al. 117-100 Still 117-139.5

Touey 131-208 8 3,008,472 11/1961 Touey 117-l6 3,071,492 1/1963 Satterly 260233.3 3,097,561 7/1963 Stein 1l7--l6 3,191,375 6/ 1965 Naegeli 57l64 FRANK J. COHEN, Primary Examiner.

WILLIAM D. MARTIN, Examiner.

S. W. ROTHSTEIN, J. PETRAKES, Assistant Examiners. 

1. IN A METHOD FOR PREPARING YARN FROM FIBERS, THE STEP WHICH COMPRISES ADDING TO THE FIBERS PRIOR TO THE ASSEMBLING OF SAID FIBERS, BY CARDING, INTO A CONTINUOUS STRAND, A FINELY POWDERED, FREE FLOWING STARCH PRODUCT, AND THEREAFTER SUBJECTING THE RESULTING STRAND TO A SPINNING OPERATION FOR PRODUCING THE YARN FROM SAID STRAND. 